Protecting means for electric circuits.



A. HERZ- PROTECTING MEANS FOR ELECTRIC CIRCUITS.

Patented Jan. 23,1917. 3 SHEETS-SHEET I- APPLICATION FILED OCT. 2. I915.

A. HERZ. TING MEANS FOR ELECTRIC cmcuns. APPLlCATlON HLED 0CT.2.1915.

, I PBOTEC 1 213,365.

Patented Jan. 23, 1917.

3 SHEETS-SHEET 2.

A. HERZ. PROTECTING MEANS FoR ELECTRIC CIRCUITS.

APPLICATION FILED OCT. 2. 1915.

Patented Jan. 23, 1917.

3 SHEETS-SHEET 3- TED STATES PATENT OFFICE.

ALFRED HERZ, OF CHICAGO, ILLINOIS, ASSIGNOR TO DELTA-STAR ELECTRIC COMlPANY, 7

OF CHICAGO, ILLIN 018, A CORPORATION OF ILLINOIS.

Specification of Letters Patent.

Patented Jan; 23,1917.

Application filed October 2, 1915. Serial No. 53,667.

To all whom it may concern;

'Be it known that I, ALFRED Hnnz, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Protecting Means for Electric Circuits, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to protecting means for electric circuits, and aims to provide an improved potential surge protector for transmission linesand the like.

The problem of protecting transmission lines and central or substation apparatus from potential surges has always been of importance. As the capacities of power systems have been increased and higher voltages employed, the problem has become acute. In a system of large capacity, the switching operations may become of such size and involve the sudden changeof such large forces that disturbances capable of serious damage, are caused. The greater the extent of the system, the greater is the possibility for damage that may be done. A short circuit upon one part of a large capacity system may be of much greater severity than if it occurred in a system of smaller capacity, and a short circuit of this nature often causes oscillation which results in high potentials and high frequency disturbances. The line or the apparatus maybe in such a condition, that upon the initiation of such oscillatory disturbances a resonant effect will be caused, and a standing wave of potential created, which is capable of great damage,

The employment ofhigh potentials greatly complicates the problem by increasing the diflicultics of insulation and by the increased effect of the condensive capacity of a system or the variousfeatures of apparatus. Horn and multigap arresters were brought out early in the development of the art, but these devices in effecting relief, often cause greater disturbances than the disturbance they are meant to correct. The electrolytic arrester often termed the aluminum cell arreste'r was then developed, and

it in conjunction'with a spark gap for se arating the arrester normally from the line,

has been accepted at this stage of the art tial, but to high tial arrester. The electrolytic cell arrester cannot advantageously be connected directly tothe line to protect the same, because of a. constant flow of current, and the'conscquent heating that results. But as it is found that the potential wave often passes by the gap, refusing to pass to ground, and going on'and damaging apparatus on the line beyond the arrestr, it was found essential to provide some means for tential wave to jump the gap and go to' ground through the arrester. For thispurpose choke coils are installed in series; in the line and the arrester'is installed on the side of the coil upon which the disturbance originates, so thatthe potential wavewill be'halted or checked to the extent required to compelit to go to ground. The choke coils are of low impedance for normal frequencie and for gradual changes of potenof very considerable inithe very thing that fronts, they are pedance. However,

as an efiicacious type of lightning or potencompelling the pofrequencies or steep :wave

makes a choke coil valuableto localize the-8 0 effect of a disturbance, also localizes the influence of the protective device. A disturbance arising on the opposite side of the choke coil is completely shut ofi' from the arrcster, as a consequence that side of the line or result has been has been installed on atransmisslon line other than at the end of'the line enterin system is entirely unprotected. The

that generally no arrester v i a station. But all the dangerousrises o potential do not arise upon the transmission 7 system and I have observedthat potential surges f considerable magnitude often appear within the station, and. as they occur on the high potential bus 'bars and haw e omiortunity for damaging a number of costly pieces of apparatus, they are very dangerous. It is also to be noted that this condition is extremely dangerous men or attendants in a station.

I have observed the formation of waves of potential within a station due to 21. peculiar resonant condition .of the system and apparatus. As the choke coils ofthe' various feeder lines shut off the potential from discharging through any of the arresters,

the potential is built up until it becomes so gr at thatsomething gives way andserious damage results. i My invention aims to glve complete pronection of the electrolytic arrester through a horn gap to each side of a choke 0011.. Fig. 2 is a similar diagram illustrating inv addition, the charging resistance which may be employed to charge the electrolytic arrester. Fig. 3 illustrates diagrammatically.

a protective system employing a multigap arrester. Fig. 4 illustrates a system in which the gap electrodes are adjustable with respect to each other. Fig. 5 isa diagram of a system employing a different type ofarrester. Fig. 6 illustrates a pair of gapsin which the common electrode is connected to ground through an improved form of ,re-' Fig. 7 illustrates the manner in which the apparatus may be installed a pole or thelike.

sistance.

grammatically the connection of the arrester to a three phase system. Fig. 9 illustrates my invention applied to the metering apparatus of a branch circuit. Fig. 10 is a' diagram of a high potential bus bar with a number of feeder lines leading ofi to various feeder circuits and a common lightning bus bar for .the same. Fig. 11 is a fragmentary elevation of a type of horn gap which I employ. Fig. 12 is a sectional view of one of the horns. Fig. 13 is a diagram illustrating the application of my invention, and Fig. 14 is a perspective view of a 'form of end clip employed to grip the ends of adjacent resistance rods for the resistance arrester. of the type shown in Figs. 5, 6 and 7.

In Fig. 1'I have shown the choke coil 1 connected in series with the line, leading on one side 'by means of the wire 2 to the high tension bus in the station, and on the other side by wire 3 to the feedercircuit. The

line '3 is connected to the horngap electrode 4, the other electrodeibeing connected to the electrolytic cell or cells 6 which I term the electrolytic arrester. The electrolytic arrester -6 has a ground conmotion 7 for di'scliargingthc potential to ground The wire 2 which leads to the bus is connected to a horn gap electrode S'whi'ch has a'gcoiiperating electrode; 9, also ""conchokej coil "-is thus'- provided witlaa normally-"ope 'shuntQthis' shunt being gpen at the spark eso"; ed by the electrodes 4,

a entralfpart of. the shunt Figure l is a diagram illustratin'g the conupon Fig. 8 illustrates iav the electrolytic arrester: 6"; {The breaking the dynamic are. I

'are'adjustableso that difi'e'rent speeds-of is connected to ground through a current limiting device 6, in this case indicated as an electrolytic cell orcells.

A potential wave arising on the feeder line 3 will travel toward the choke coil 1,

the impedance of which will be so great and thence to ground 7. Similarly a dis turbance arising within the central station or on the high potential bus will travel toward the choke coil 1 but will be prevented from going out on the line by the choke coil, and will'then discharge across the gap 8, 9 to the electrolytic ar'rester 6 and thence to ground. If the disturbance is of a very serious character some of the potential may travel across both gaps 4, 5 and 8, 9 but the wave will be so flattened out by such action that no serious damage will be done by such wave after traversing the gap. In case .of total failure of a particular arrester the line is not'totally deprived of protection as the normally open shunt about the inductance coil; bypasses the surges to the other side of the line where the same may v be either absorbed in the line or passed on to the nearest arrester. 1A certain amount ofthe energy is at the same time dissipated in the ga s in the shunt. The gaps are preferably a justableso that they may. be set fgr diilerent values ,on opposite sides of t e 'choke'coil 1. In Fig. 2 I have shown a slmilar 'scheme in which I employ an auxmay" electrode 10' and a charging resist ance ll' for charging the electrolytic arrester 6-. It is a well known fact that the electrolytic "arrester to be effective should be charged by application of potential of the lines thereto at regular intervals so as to maintain the film upon the aluminum cells of the arrester. Only one of the horn gaps ion need be supplied with the charging resist v ance. It is obvious that either the electrode 4 or the electrode '8 may thus be supplied -with the auxiliary electrode and resistance.

When the aluminum cell 6is to be charged the horn electrodes 5 and 10 are connected in any well knownmanner so thatcharging current'flows from the line through the resistance ,1 and the aluminum cell 6 in series to ground.

gap arrester 12 which is connected to ground 7 at its lower end and at its upper end is connected to the middle point of a resistance 12. In'steadof employing horn gap elec- In the system of Fig. 3 I employ a multi-,

inultigaparrester 12 is depended upon for.

The electrodes action may be obtained on opposite sides of the choke coil 1. The resistance l2 'plays an manner a potential wave arising in the station will'have an opportunity for discharging to ground '7 or for discharging part of the same to the line 3 in order to dissipate its energy as rapidly as possible.

In the system shown in Fig. 4 T have connected the line 3 to an ad3u'stable horn gap electrode 13. and the bus side 2 to the adjustable horn gap electrode 14. Another adjustable horn gap electrode 15 is common to both the electrodes 13 and14, and is con-' nected to the electrolytic arreste'r 6 to ground at 7. The three electrodes form an adjustable spark gap between the sides of the line and between each side of'the line and ground.

In Fig. 5 T have illustrated a well known type of arr-ester as applied to the 'choke'coil 1. The horns 4 and 5 are connected to the line and bus bar respectively and the central electrode 16 is connected to ground at 7. This electrode comprises a series of short metal sections 17 connected together by a resistance 18.

In Fig 6 I have illustrated an improved structure in which the horn electrodes 5 and 9 are connected together at their top, being formed out of a single piece of metal and connected through a resistance to ground at The resistance is built'up of a number of resistance rods 19 connected together at their outer ends by suitable metallic clips 20. These resistance rods 19 are mounted in a block of porcelain 2]., which supports at its upper end a bracket 22vbearing the electrodes 5 9. The porcelain block 21 is mounted upon a cross arm or suitable support. A discharge taking place across the gap 4, 5 will pass through the bracket to the first resistance rod 19, and if the discharge is of considerable gravity it will jump the gap between successive metal clips 20 and pass directly to ground at 7. After the passage of the discharge the current will tend to follow the path of the'resistance rod and will thus be limited to a safe value. If a resistance rod 19 breaks, it does not disable the arrester as the end will drop down upon the next resist- A ance or if broken completely away the arc or discharge willjump across the gap between adjacent ends and operate normally.

Fig. 7 shows the manner in which a commercial installation may be made. The electrodes 4 and 8 are mounted upon insulators 22 and 23 which are secured by suitable pinsto a bar or piece of channel iron 24. The bar'24 may be secured to the electrodes.

cross arm or a pair of cross arms on the pole 25. The'electrodes 5 and 9 are supported upon an insulator 26 which is also mounted upon the bar 24. These electrodes 5 and 9 are connected to the resistance 27 which is constructed in a manner similar to the resistance shown in Fig. 6. The resistance rods 19 are secured together by means of metal clamps 28 shown in Fig. 14. The con nect-ing pieces 28 are provided with clamps 29 for'grlpping the ends of, the resistance rods. A lug or bracket 30 is provided for securing the connecting pieces 28 to a suitable baseboard or slab of slate marble or the like which may be mountedupon the pole 25. The lowermost clip is connected. to the ground connection 7. Thehorn electrodes 4, 5 and 9, 8 may be constructed as shown in Fig. 11. The electrode there shown consists of a stamping 58 of sheet metal for giving a curved face. At the point where the so that at this minimum air gap 59, the electrodes will present toward each other substantially spherical surfaces. As is well known, the voltage required to break down the gap between spherical surfaces is more nearly constant than between other forms of The sheet metal electrodes 58 air gap is the least the electrode is curved may be reinforced and supported by suitable castings 60 which may be riveted to the sheet metal part. The reinforcing bracket 60 is secured to an arm 61 and supported on the top of an insulator as'shown.

In Fig. 13 I haVeshoWn the manner in which a number oflines, and the bus bar to which they are connected, may be protect-. ed by a single electrolytic arrester or.battery of arresters. The bus bar 32 is con nected through an oil switch 33, and through the current transformer 34 with the step-up transformer 35, the other side of which is connected to the generator. The outgoing feeder lines 36 and 37 are fed by the bus bar 32. The feeder line 37 is connected through an open air switch 37 to the choke coil 38. the other side of which is connected to the bus bar 32. through the current transformer 39, and the oil switch 40. The bus bar 32 is connected by the open air switch 41 to the horn electrode 42 which has a coiiperating electrode 43 connected to the arrester bus 44. The feeder .37 is also connected by an pen air switch 45 to one of the electrodes 4340f a suitable horn gap, the other electrode 4 7 being connected to the arc rester bus 44. The feeder 36 which is supplied with apparatus similar to the feeder 37 connected by an open air switch 48 o the horn electrode 49,. the coiiperating horn 50 being connected to the arrester bus 44. The arr-ester bus 44 is connected to the electrolytic cell arrester 6 which is grounded at 7. It can be seen that a disturbance arising anywhere on the system has free access to practicable for protecting .b'oth' the arrester apparatus without passing through any of the central station apparatus. In a similar inanner, a disturbance arising Within the station has an opportunity to discharge through the electrolytic arrester without injuring the central station apparatus or Without placing a dangerous potential upon the line.

The system shown in Fig. is more extensive than the system shown in Fig-1,3 in that a greater number of feeders 3", 3*, 3, 3, and 8, are connected to the high tension bus. The high tension bus is divided or sectionaliz ed into a niunber of parts 53 and 54, each section being fed by a separate transformer 52 and 51 respectively. Each .section of the high tension'bus is connect ed through a horn gap 55 or 56 to the arrester bus 57 which is connected through the electrolytic arrester 6 to ground at 7. The sections of, the bus may be'connected together by a suitable switch 58. Each of the lines, 3, 3", etc., is connected by a suitable horn gap to the arrester bus 57 so that complete protection may be had, both for the central station-and for the transmission lines by employingasingle electrolytic arr-ester 6.

Fig.. 8 illustrates the manner in which protection for the feeders and central station apparatus or incoming lines and substation apparatus may be obtained. The system isa three phase system .emplo fig four arresters so that the single groun ed arrester is connected in series with one of the others when a discharge occurs from" the line to ground. Each of the three line wires 61, 62 and 63 is provided with a choke soil in series therewith and. a line on each side of the choke coil is controlytic arresters,64, 65'and 66 respectively, and each of these electrolytic arrestersis connected in series with the grounded arrester 67. The arresters 66 and 67 are pro vided with a change-over switch 68' for charging the same.

'Fig. 9 illustrates diagrammatically how. the invention may be applied to protect. any

turbances originating on opposite sides thereof. Where a feeder branch is ledoff into territory in which the operatingcom any does notmaintaina substation, esirable to meter the output to this ub; feeder at a point adjacent to the mainttrans mission line. The metering mechafni subjeet to disturbances arising 'u transmission line or' upon the fef so Heretofore no scheme of protecti i o the metering equlpment. "Accordingfto m ia;

vention I connect teenager en, both-sides #5,; in combinatio 9 the meterleg q ipment e Ea ng b iriet 1 Plur r. r mg cholre C0115 76 and reach sideig i tardfation la "nneete in'serics W1 h'the 3 0 at metering apparatus. In some cases I. -depend upon the impedance of the series.

- the line against crease in eflicien'cy of the entire system is ob grounded neutral I -trolytic arrester. I

nected to a suitable horn gap, the common. electrodes of which are connected to the electrodes mountedon said insulators, connect .mg wlres for ]01I11I1g said horn electrodes topiece of apparatus which is .sub ect to dishorn elect odes and agroundconnection for.

it is parallel transformer 72 to cause the potential Wave to jump the gap and go to ound through the arrester 6. The feeder 6 may be connected or disconnected from thetransmis-' sion line 74 by means of the switch 77. This scheme of protection may be employed. not only to the metering equipment 73 but to i any other piece of apparatus upon the line. 75 It may even be found desirable to protect insulators at particularlyexposed points on destruction by the above invention. v It can be seen from th -jabove description that I have provided a very .eficient scheme of protection against potential surges,lightning discharges and the like at a cost far, below any system heretofore devised. The protection thus rendered is far more eff/ed; tive than has been found possible heretofore in the art, and due to eliminating shut! downs and destruction of apparatuman in tained.

What I'claim is: b 1. In combination, a transmission'linepa bus, surge retarding means between said line and said bus, an electrolytic arrestea; having a ground. connection, separate sparl'zgaps connecting said electrolytic .arrester to each side of said surge retarding means and a charging resistance for charging said elec- 2. In a horn gap arrester, a horn frmed ice of a curved channel of sheet metal, said channel being bent" to present a spherical i face at the polnt of discharge formatlon, and y means fitting into the concave side. of said-'2 channel for supporting said ho (Ti-'3 I 3." In combination. a supporiiiiig'bracketfl an inductance coil; an insulator for susperide ing said coil below said bracket, a pair of insulators above said bracket, horn gap clean the terminals of said coil, athird insulators. mounted between said latter two in'sulatori above said bracket, horn electrode meansforf i forminga pair of gaps'with said horn elec- 111"5 trodes, t ansmissionwires-connected to'said,

electrode means said t. In atlightning arrester, a pluratity of r slst n 'm t 'e al 9 31Ja e gae ends fsaidrode in seri s 's i clips o i ageac 'ia-hast ai a a pai a.

lgetaf bolts fon'sprin'ljng ut lise-skate" .atl' eenda Said-r0. S, d lip it 1 elvl'iem te sa i se k s d be r a mg a sm'ge projecting Tater e up -eras re i tion, means n shunt of each inductance or retardation coil for dissipating and lay-passing said disturbances arising upon a section, whereby said disturbances may be discharged to ground or a part of the samedischarged to an adjacent section of the line, said meanscomprising an electrode connected to one side of the inductance coihan electrode connected to the other side of the inductance coil, electrode means between said electrodes and adapted to form independent spark gaps with said electrode, a ground connection for said electrode means and means for resisting or limiting the passage of dynamic current through said grounded connections.

pacity around said inductance coilfor relieving disturbances arising upon either side of said coil, said open shunt including a pair of spark gaps, the central part'ot said shunt between said iark n is being rounded andv means for limiting the flow of dynamic current from said central part of the shunt to ground.

7. In combination an electrical transmission line to be protected, said line being divided into adjacent sections, said adjacent sections being separated by surge retarding means tending to localize or confine a disturbance in the section in which it arises, said means comprising an inductance coil connected in series with each ad acent section, means in shunt of said inductance coil for dissipating the disturbances arising upon either of the adjacent sect-ions, said means comprising a spark gap electrode connected to one terminal of said inductance (3011, another spark gap electrode connected to the other terminal of the inductance coil and c0' operating spark gap electrode means between said electrodes and adapted to form independent spark gaps with said electrodes in said shunt, a ground connection for said electrode means and means for resisting and limiting the passage of dynamic current from said electrode means to ground, said shunt being organized to permit the by-passing of part of a disturbance around said inductance coil to the adjacent section in the event of a failure of said ground connection to discharge said disturbance to ground.

8. In combinationa transmission line to be protected, said line-having surge limiting means connected in series 'with a dynamic current normally passing along the line, said surge limiting means comprising an inductance coil tending to prevent surges from passing along the same path as the dynamic current, thereby tending to localize the disturbance, a normally open shunt of large capacity about said inductance coil for relieving disturbances arising upon either side of said coil, each-side of said open shunt terminating in a spark electrode, a ground connection having electrode means lying electrically between said electrode and means for limiting the dynamic current which tends to follow a discharge from said shunt to ground. In witness \vhereof, I hereunto subscribe my name this 27th day of September A; D.

' ALFRED HERZ. 

